The present invention relates to a shelf stable silicone caulking composition utilizing emulsion prepared by the anionic polymerization of a cyclopolydiorganosiloxane, a polyfunctional organosilane, a tin condensation catalyst, a nonsiliceous filler, such as calcium carbonate, and tetraalkylorganoguanidine as a stabilizer.
Prior to the present invention, as shown by M. G. Elias et al., U.S. Pat. No. 4,427,811, an improvement in the manufacture of silicone emulsion convertible to elastomer having enhanced physical properties was achieved by incorporating filler into the emulsion after it had aged at least two weeks at room temperature, particularly where the filler was other than colloidal silica. A further improvement in silicone water-based elastomeric caulking materials is shown by A. L. Freiberg, U.S. Pat. No. 4,608,412, where a nonsiliceous filler, such as calcium carbonate, was incorporated into the emulsion when freshly made to produce a caulking material having a useful shelf life providing the caulking material also contained 2-amino-2-methyl-1-propanol.
The present invention is based on our discovery that shelf stable silicone caulking compositions, which yield elastomers upon removal of water, can be made by combining a nonsiliceous filler, such as calcium carbonate, with an emulsion prepared by the anionic polymerization of cyclic polydiorganosiloxane, along with a polyfunctional organosilane, certain tin condensation catalyst as defined hereinafter, and a tetraalkylorganoguanidine, as a stabilizer. The caulking compositions also have been found to provide silicone elastomers exhibiting excellent physical properties.